1. Field of the Invention
The present invention relates generally to a process for plugging subterranean flow paths of aqueous solutions and more particularly, but not by way of limitation, both to correction of permeability variation in oil-bearing formations and to the prevention of aqueous contaminant outflow at sites of subterranean contamination.
2. Description of Prior Art
Available prior art is primarily associated with correction of permeability variation in waterflooded oil fields. After injection of water into a subterranean oil-bearing formation to drive oil toward a recovery well, a problem of stratification frequently occurs because of permeability variation in oil-bearing rock formations. Stratification arises when injected water flows along the subterranean paths of least resistance, forming waterswept zones, and bypasses many zones of embedded oil. The waterswept zones are depleted of recoverable oil before the bypassed zones and the oil yield of continued waterflooding dramatically decreases.
One approach to the correction of permeability variation that causes oil field stratification has been the injection of inert plugging agents such as cement, colloidal clays, organic resins and gels (see for example, Danielson et al, Producers Monthly 15 No. 1, p. 15 [November, 1950]). U.S. Pat. No. 3,844,348, issued to Stratton, discloses a method of reducing the fluid permeability of a porous subterranean formation by treatment with a Xanthomonas derived heteropolysaccharide modified by addition of a synthetic polymer.
U.S. Pat. No. 3,340,930, issued to Hitzman, discloses a method of enhancing oil recovery by injection of oil-metabolizing and detergent-producing bacteria of the classes Actinomycetales and Schizomycetes.